Structural glass element and method for its production

ABSTRACT

In the case of a structural glass element with a plastic-coated glass panel and at least one assembly element attached hereon, the glass panel is coated in particular with a silicone-based elastomer across its entire surface, and the coating at the same time creates an adhesive joint with one section of the assembly element supported on the glass panel.

TECHNICAL FIELD

The invention relates to a structural glass element with aplastic-coated glass panel and with at least one mounting elementattached hereon, as well as a method for producing such.

PRIOR ART

Facades and roofing, which consist either entirely or at any rate to asignificant extent of glass, have become an integral part of modernarchitecture. They are mostly formed from flat glass panels, which areinserted into suitable (usually consisting of steel) supportingstructures. These glass panels are frequently colored and/or providedwith functional coatings, such as to keep away infrared radiation fromthe inside of a building or to realize certain optical effects.

Glass panels with vapor-deposited thin films are particularly known,which increase the reflection capacity and the infrared range and partlyalso in the visible range and in the UV range. To produce high qualityglazing, which has an opaque appearance, a complex and expensivestripping treatment of the glass surface is normally performed.

It is also known from U.S. Pat. No. 4,814,230 or from U.S. Pat. No.7,309,734 B2, for example, to produce opaque glass panels or such withparticular optical characteristics by the application of apigment-containing elastomer coating, which can certainly satisfy thehigh quality requirements.

DISCLOSURE OF THE INVENTION

The invention provides a structural glass element with the Features ofClaim 1. Furthermore, multiple methods for its manufacture are stated.

One aspect of the invention is that a coating, primarily used forcreating optical effects, of a glass panel provided as a structuralelement is simultaneously used for purposes of mounting. That is whythis means in particular a departure from the usual course of action oneskilled in the art would take, because coatings with mounting action(especially adhesive coatings) are normally formed only in partial areasof larger parts, which are required for adequate transmission of force.With the coatings at issue however the plastic coating is typically, butnot necessarily, applied on the entire surface of the glass panel. Usingthese coatings at the same time for firmly bonding a mounting elementonto the glass panel is an equally surprising as well as advantageousidea. This idea facilitates significant simplifications and cost savingsin the production process, because an additional application of adhesivewhich must moreover be typically exactly locally limited, is no longernecessary.

A further advantage of the invention consist in that the plastic coating(especially a silicone-based elastomer coating) which must be formedrelatively thick for the purpose of attaching the mounting element,improves the fracture behavior of the structural glass element and makesit easier to comply with safety regulations. The elastomer coatingretains fragments up to a certain degree within the bond structure ofthe structural element and it can therefore contribute to prevent themfrom falling down or flying away.

In one embodiment of the invention, the supported section of the or eachmounting element is formed by a perforated metal sheet, the holes ofwhich are penetrated at least partially by the coating of the glasspanel. This embodiment is flexible in its application, because a largevariety of simple perforated metal sheets are commercially availableinexpensively, and facilitate a particularly close positive engagementbetween the glass panel and the mounting element as well as obtaining avery high joint strength.

A further embodiment of the invention provides that the surface of theglass panel is covered by more than a quarter, particularly by apredominant portion of the surface, with the supported section of themounting element or the supported sections of multiple mountingelements. This permits a good, advantageous distribution of power duringthe assembly of the structural glass elements and prevents peak loadsand the risk of resulting fracture.

In a further embodiment, the mounting element or at least one mountingelement includes a mounting bracket projecting upright from thesupporting section. The mounting brackets can be formed in atechnologically simple and cost-effective manner by bending the edges ofthe preferably used perforated metal sheet and can (provided withcorresponding openings) be flexibly used for different assemblysituations.

In further embodiments of the invention, the coating has a thickness inthe range between 1 and 7 mm, in particular in the range between 2 and 5mm. The coating of the glass panel therefore involves a thick coating,the exact thickness of which must be determined depending on thethickness and size of the glass panel and the specific allocation ofmounting elements according to the assembly requirements.

In a further embodiment, the coating is densely colored or pigmentedsuch that the visible area of the structural glass element isnon-transparent and covers the or each mounting element. This ensures anoptically high-quality appearance of a facade or reconstruction orsimilar formed with the structural glass elements, irrespective of theactual configuration of the substructure and allocated mountingelements. If the coating has a specified preferred thickness, it can inparticular also be colored or pigmented white and at the same time coverany substructure; this is obviously likewise applicable for a black orcolored pigmentation or coloring.

In the case of the coating of the structural glass element, thisparticularly involves a silicone-based elastomer or a silicone coating,i.e. that the starting material for the coating is a siliconecomposition.

Silicone compositions that are particularly suitable for the coating arein particular condensation cross-linked two-component siliconecompositions. Preferably this will be a two-component siliconecomposition consisting of a component A, comprising

-   -   at least one hydroxyl group terminated polydiorganosiloxane P;        and a component B comprising    -   at least one cross-linking agent for polydiorganosiloxanes; as        well as    -   at least one catalyst for the cross-linking of        polydiorganosiloxanes.

Suitable polydiorganosiloxanes are in particular polydiorganosiloxane Pof the formula (I),

whereinthe radicals R¹, R² and R³ stand independently of one another for linearor branched, mono-valent hydrocarbon radicals with 1-12 C atoms, whichpossibly exhibit one or several hetero atoms and possibly one or severalC—C multiple bonds and/or possibly cycloaliphatic and/or aromaticcomponents;the R⁴ radicals stand independently of one another for hydroxyl groupsor for alkoxy, acetoxy or ketoxime groups with 1-13 C atoms each, whichpossibly exhibit one or several hetero atoms and possibly one or severalC—C multiple bonds and/or possibly cycloaliphatic and/or aromaticcomponents;the index p stands for a value of 0, 1 or 2; andthe index m is selected such that the polydiorganosiloxane P comprises aviscosity of 10 to 500,000 MPa at a temperature of 23° C.The R¹ and R² radicals stand in particular for alkyl radicals with 1 to5, in particular with 1 to 3, C atoms, preferably for methyl groups.The index m is furthermore particularly selected such that thepolydiorganosiloxane P has a viscosity of 1000 to 100,000 MPa at atemperature of 23° C. The viscosity is typically determined pursuant toDIN 53018.

If the polydiorganosiloxane P in the component A of the two-componentsilicone composition is a hydroxide group terminatedpolydiorganosiloxane, the index p typically stands for a value of 2.Hydroxyl group terminated polydiorganosiloxanes are known andcommercially available. The manufacture of such polydiorganosiloxanes isalso done in the known manner. This is described in U.S. Pat. No.4,962,152, for example, the disclosure of which is herewith incorporatedby reference.

If the polydiorganosiloxane P in the component A of the two-componentsilicone composition is a polydiorganosiloxane P of the formula (I), inwhich the R⁴ radicals stand for alkoxy, acetoxy or ketoxime groups,these are particularly alkoxy or ketoxime groups. Then the index pstands in particular for a value of 0 or 1.

Preferred alkoxy groups are methoxy, ethoxy or isopropoxy groups.

Preferred ketoxime groups are dialkylketoxime groups the alkyl groups ofwhich exhibit respectively 1 to 6 C atoms. The two alkyl groups of thedialkylketoxime preferably stand independently from one another formethyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl groups.Especially preferred are those cases, in which one alkyl group of thedialkylketoxime stands for a methyl group and the other alkyl group ofthe dialkylketoxime stands for a methyl, ethyl or for an isobutyl group.The ketoxime group most preferably stands for an ethyl methyl ketoximegroup.

The component B of the two-component silicone composition includes atleast one cross-linking agent for polydiorganosiloxanes. Thecross-linking agent is in particular a silane of the formula (II).

In this context, the R⁶ radical stands independently of one another fora linear or branched, mono-valent hydrocarbon radical with 1-12 C atoms,which possibly exhibits one or several hetero atoms and possibly one orseveral C—C multiple bonds and/or possibly cycloaliphatic and/oraromatic components.

The R⁷ radical stands independently of one another for a hydrogen atom,or for an alkyl radical with 1 to 12 C atoms, or for an oxime radicalwith 1 to 12 C atoms, or for an acyl radical with 1 to 12 C atoms. TheR⁷ radical particularly stands for an alkyl residue with 1 to 5, inparticular 1 to 3, C atoms, preferably for a methyl or for an ethylgroup.

The index s stands for a value of 0 to 4, in particular for a value of0, 1 or 2, preferably for a value of 0.

Selecting the silane of the formula (II) as cross-linking agent forpolydiorganosiloxanes, different requirements can be decisive for thesilicone composition. The reactivity of the silane can play an importantrole on the one hand, wherein on the other, higher-reactive silanes arepreferred, in principle. But on the other hand, even toxicologicalreasons can be decisive for the selection of the cross-linking agent.For that reason, tetraethoxysilane is preferred as cross-linking agentcompared to tetramethoxysilane, for example.

Examples of suitable silanes of the formula (II) aremethyltrimethoxysilane, chloromethyltrimethoxysilane,ethyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane,methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane,methyltripropoxysilane, phenyltripropoxysilane, tetramethoxysilane,tetraethoxysilane, tetra-n-propoxysilane or tetra-n-butoxysilane. Thesilane of formula (II) is particular preferably vinyltrimethoxysilane ortetraethoxysilane, or a mixture thereof.

The silanes can furthermore also already exist partially (a part of allR⁷═H) or completely hydrolyzed (all R⁷═H). Because of the greatlyincreased reactivity of partially or completely hydrolyzed silanes,their use as cross-linking agents can be advantageous. In this context,one skilled in the art knows that when using partially or completelyhydrolyzed silanes for the formation of oligomeric siloxanes, it ispossible that particularly dimers and/or trimers can be formed, whichare formed by the condensation of hydrolyzed silanes. Consequently, evenoligomeric siloxanes can be used as cross-linking agents for thetwo-component silicone composition. Suitable oligomeric siloxanes, forexample, are hexamethoxydisiloxane, hexaethoxydisiloxane,hexa-n-propoxydisiloxane, hexa-n-butoxydisiloxane,octaethoxytrisiloxane, octa-n-butoxytrisiloxane anddecaethoxytetrasiloxane.

It is obviously also possible to use any mixture of the above-mentionedsilanes as cross-linking agents for the two-component siliconecomposition.

The proportion of the cross-linking agent for polydiorganosiloxanes ispreferably 0.1 to 20% by weight, in particular 1 to 15% by weight,preferably 2 to 10% by weight of the total silicone composition.

Regarding the catalyst for the cross-linking of polydiorganosiloxanes,this will particularly be an organotin compound, or a titanate, or acombination thereof.

Preferred organotin compounds are dialkyltin compounds, such as they areselected for example from the group consisting ofdimethyltindi-2-ethylhexanoate, dimethyltindilaurate,di-n-butyltindiacetate, di-n-butyltindi-2-ethylhexanoate,di-n-butyltindicaprylate, di-n-butyltindi-2,2-dimethyloctanoate,di-n-butyltindilaurate, di-n-butyltin-distearate,di-n-butyltindimaleinate, di-n-butyltindioleate, di-n-butyltindiacetate,di-n-octyltindi-2-ethylhexanoate, di-n-octyltindi-2,2-dimethyloctanoate,di-n-octyltindimaleinate and di-n-octyltindilaurate. Compounds arereferred to as titanates or organotitanates, which exhibit at least oneligand that is bonded to the titanium atom by means of an oxygen atom.Ligands bonded to the titanium atom by means of an oxygen/titanium bondare particularly those that are selected from the group consisting ofthe alkoxy group, sulfonate group, carboxylate group, dialkyl phosphategroup, dialkyl pyrophosphate group and acetylacetonate group. Preferredtitanates are tetrabutyl titanate or tetraisopropyl titanate, forexample.

Furthermore suitable titanates exhibit at least one multi-dentateligand, also called chelate ligand. The multi-dentate ligand ispreferably a bidentate ligand.

Suitable titanates are commercially available from the DuPont Company,USA, under the trade names of Tyzor® AA, GBA, GBO, AA-75, AA-65, AA-105,DC, BEAT, IBAY.

It is obviously possible or even preferred in certain cases to usemixtures of different catalysts. The catalyst is a mixture of anorganotin compound with a titanate, for example.

The percentage of the catalyst for the cross-linking ofpolydiorganosiloxanes is preferably 0.001 to 10% by weight, inparticular 0.005 to 4% by weight, preferably 0.01 to 3% by weight of theentire two-component silicone composition.

The two-component silicone composition can possibly still containfurther constituents.

Such type of additional constituents are in particular softeners,inorganic and/or organic filler materials, curing accelerators,pigments, adhesion promoters, processing resources, rheology modifiers,stabilizers, dyes, inhibitors, heat stabilizers, antistatics, flameretardants, biocides, waxes, flow-control agents, thixotropic agents,and further known raw materials and additives known to one skilled inthe art.

Further suitable constituents, in particular adhesion promoters andsofteners, which can be contained in the two-component siliconecomposition, are described in paragraphs [0051] to [0055] of the patentapplication US 2010/063190 A1, for example, the entire disclosure ofwhich is herewith incorporated by reference.

During the use of such type of optional constituents, it is important tonote that constituents, which may impair the storage stability of thecomposition as a result of inter-reaction or reaction with otherconstituents, are separately stored.

It is furthermore advantageous to select all previously mentionedconstituents which may also be contained in the two-component siliconecomposition such that the storage stability of both components of thetwo-component silicone composition will not be affected negatively bythe presence of such a constituent, i.e. that the properties of thecomposition, in particular the application and curing properties, willnot change during storage or only very slightly. This requires that anyreactions resulting in the chemical curing of the describedtwo-component silicone composition will not occur to a significantdegree during the storage.

Trialkylsilyl-terminated polydialkyl siloxanes are particularly suitableas softeners, in particular trimethylsilyl-terminated polydimethylsiloxanes. Trimethylsilyl-terminated polydimethyl siloxanes withviscosities between 1 and 10,000 MPa are preferred. Particularlypreferred are viscosities between 10 and 1000 MPa. However, it is alsopossible to use trimethylsilyl-terminated polydimethyl siloxanes, inwhich some of the methyl groups are substituted by other organic groupssuch as phenyl, vinyl or trifluoropropyl. Although preferably preferredlinear trimethylsilyl-terminated polydimethylsiloxanes are used assofteners, also branched compounds can be used. Such branched compoundsare created by the fact that small quantities of trifunctional ortetrafunctional silanes are used in the base materials for theirmanufacture. But is also possible to use other organic compounds insteadof the polysiloxane softeners, such as certain hydrocarbons or mixturesthereof, as softeners. Such hydrocarbons can be aromatic or aliphatic.During the selection it must particularly be ensured that thesehydrocarbons have low volatility and sufficient compatibility with theother constituents of the silicone composition. The percentage of thesoftener is preferably 2 to 15% by weight, in particular 5 to 10% byweight, of the entire two-component silicone composition.

The composition can furthermore comprise at least one filler material.The filler material influences the rheological properties of the uncuredcomposition as well as the mechanical properties and the surfacecondition of the cured composition. A filler material can furthermoreinfluence the appearance of the silicone composition, particularly inthe cured condition.

Suitable filler materials are natural, ground or precipitated calciumcarbonates, for example, which may have been coated with fatty acids, inparticular stearic acid, calcined kaolins, aluminum oxides, aluminumhydroxides, silicic acids, in particular highly dispersed silicic acidsfrom pyrolysis processes, carbon black, particularly industriallyproduced carbon black, aluminum silicates, magnesium aluminum silicates,zirconium silicates, silica flour, cristobalite flour, diatomaceousearth, mica, iron oxides, titanium oxides, zirconium oxides, gypsum,annalin, barium sulfate (BaSO₄, also called barite or heavy earth),boron carbide, boron nitride, graphite, carbon fibers, glass fibers orhollow glass spheres, the surface of which may have been treated with ahydrophobic agent. Preferred filler materials are calcium carbonates,calcined kaolins, carbon black, highly dispersed silicic acids as wellas flame retarding filler materials, such as hydroxides or hydrates, inparticular hydroxides or hydrates of aluminum, preferably aluminumhydroxide.

In a preferred embodiment, the silicone composition contains highlydispersed silicic acids from pyrolysis processes or calcium carbonate asfiller material.

It is absolutely possible and can even be an advantage to utilize amixture of different filler materials.

A suitable filler material quantity is in the range of 1 to 40% byweight, in particular 5 to 30% by weight, preferably 10 to 20% byweight, for example, relative to the entire two-component siliconecomposition.

In a likewise preferred embodiment, the two-component siliconecomposition contains none or only small quantities of filler materials.

In a particularly preferred embodiment, the two-component siliconecomposition contains a preparation for dyeing of the compositions,wherein this preparation in particular is a color paste or a pigment.

During the application of the two-component silicone composition, thecomponents A and B are mixed together, for example by stirring,kneading, rolling or suchlike, or in a mixer or by means of a staticmixer, which results in curing the composition. The curing of thetwo-component silicone composition occurs particularly at roomtemperature.

The two-component silicone composition is particularly used such thatthe weight ratio of the component A to component B is >1:1, inparticular from 3:1 to 15:1, preferably from 10:1 to 13:1.

In a variant of the proposed method, a starting material of the coatingis poured or sprayed onto the glass panel in the liquid condition, suchthat a level surface is formed by flowing. In another embodiment it canbe provided that the starting material of the coating is wiped onto theglass panel with a doctor blade in the liquid or pasty condition. Even alargely self-leveling pouring or spraying of the still (viscous) liquidcomposition followed by subsequent wiping-on with a doctor blade ispossible to compensate for any differences in levels that may stillexist. Alternatively, the method can be designed such that the startingmaterial of the coating is rolled onto the glass panel in the pastycondition, wherein in particular a plastic film is inserted between thesurface of the starting material and the surface of the coating roller,which is pulled-off again after the application and prior to the curingof the coating. This will prevent that the material will adhere to therolling surface.

In one development of the mentioned embodiments, the liquid or pastycondition of the starting material will at least be adjusted among otherthings by adjusting a preliminary reaction time prior to the applicationonto the glass panel. It should be understood that besides otherparameters, such as a solvent percentage, the temperature, etc., areimportant.

Regardless of the actual type of the application of the elastomerstarting material, the or each mounting element to be attached is putonto the formed layer “floating” (or maybe slightly impressed), as longas the starting material has not yet reacted. Depending upon thecomposition and its reaction behavior, an assembly sequence is selectedin particular which offers sufficient reserves in terms of time for afirmly bonded connection between the glass panel and the mountingelement(s) by means of the elastomer coating. It can be useful to holdthe mounting elements laterally fixed while putting them onto the stillviscous or pasty starting material layer, until such time that they areadequately fixed themselves as the layer continues to cure.

The curing of the coating, depending upon the composition thereof, canoccur sufficiently fast by air drying, but it is also possible to useinfrared heaters, maybe introducing moist air or steam or other meansknown per se for accelerating this procedure.

The invention claimed is:
 1. A structural glass element comprising a glass panel and at least one mounting element attached thereon, wherein the glass panel is coated on its entire surface with a silicone-based elastomer coating, and the silicone-based elastomer coating at the same time creates an adhesive joint with a section of the at least one mounting element supported on the glass panel, wherein the at least one mounting element comprises a metal sheet that is bent on at least one of its edges to define a mounting bracket projecting upright at an end of the metal sheet from a supported section of the metal sheet that is adhered over the surface of the glass panel, the mounting bracket being configured to be used to assemble the structural glass element, wherein the mounting element is floating on or impressed in the silicone-based elastomer coating, and wherein a starting material for the silicone-based elastomer coating is a condensation cross-linkable silicone composition comprising: a component A comprising: at least one hydroxyl group terminated polydiorganosiloxane P; and a component B comprising: at least one cross-linking agent for polydiorganosiloxanes, and at least one catalyst for the cross-linking of polydiorganosiloxanes.
 2. The structural glass element according to claim 1, wherein the supported section of one or each mounting element is formed by a perforated metal sheet, the holes of which are penetrated at least partially by the silicone-based elastomer coating of the glass panel.
 3. The structural glass element according to claim 1, wherein the surface of the glass panel is covered by more than a quarter, with the supported section of the mounting element or the supported sections of multiple mounting elements.
 4. The structural glass element according to claim 1, wherein the silicone-based elastomer coating has a thickness in the range between 1 and 7 mm.
 5. The structural glass element according to claim 1, wherein the silicone-based elastomer coating is densely pigmented such that the structural glass element is non-transparent in the visible range and the silicone-based elastomer coating covers the mounting element.
 6. The structural glass element according to claim 1, wherein the two-component silicone composition in addition comprises at least one color paste or one color pigment.
 7. The structural glass element according to claim 1, further comprising more than one assembly element.
 8. The structural glass element according to claim 1, wherein the silicone-based elastomer coating has a thickness in the range between 2 and 5 mm.
 9. A method for producing a structural glass element according to claim 1, wherein a starting material of the coating is poured or sprayed onto the glass panel in the liquid condition, such that a level surface is formed by flowing.
 10. A method for producing a structural glass element according to claim 1, wherein a starting material of the coating is wiped onto the glass panel with a doctor blade in the liquid or pasty condition.
 11. A method for producing a structural glass element according to claim 1, wherein a starting material of the coating is rolled onto the glass panel in the pasty condition, wherein in particular a plastic film is inserted between the surface of the starting material and the surface of the coating roller, which is pulled-off again after the application and prior to the curing of the coating.
 12. The method according to claim 9, wherein the liquid or pasty condition of the starting material will at least be adjusted among other things by adjusting a preliminary reaction time prior to the application onto the glass panel. 